|The Discovery of Global Warming Spencer Weart
jUNE 2006 HOME
After 1988 (a first sketch)
The closer an account of events moves toward the present, the less it displays the special virtues we seek in a work of true history, the long-view perspectives and objective analysis. Writers and readers find it hard to pick out which recent developments will really matter in the long run. We also risk accepting as factual a report that conceals errors that will only later be revealed. Worse, opinions about present-day controversies infect views of the recent past with special virulence. Therefore be wary: these sections can be only preliminary sketches.
The cutoff date for my original work on these sections was May 1, 2001. Since first placing this material online in 2003 I have made changes, mostly annually. I have added to the notes some important older references I missed, and where later work cast significant light on scientific or historical puzzles, I have expanded or modified the main text. I have also written additional sentences or entire paragraphs to summarize the most important developments since May 2001, in both the science and its social connections. Of course these afterthoughts are more journalism than historical study.
May 2001, where my "history" proper ends, is roughly the point when the draft third report of the Intergovernmental Panel on Climate Change appeared, establishing a consensus that serious warming was likely but not certain. (1*) Inevitably for such a complex issue, some scientists argued that the consensus was in error. The reservations could be expected to linger for decades, until global temperatures actually did or did not soar much too high. Since the 1980s, scientists had not been able to narrow the range of uncertainty they announced for their estimates of the most likely future warming (somewhere between one and six degrees C by the late 21st century). But they had grown far more confident that the estimates were soundly based. They also admitted that they could not guarantee there would be no "surprises" outside the announced range of uncertainty — for better or worse. Meanwhile contrarians, increasingly isolated from the reputable scientific community, continued to come up with arguments and scraps of evidence supporting the claims of powerful interests that there was no need to worry about climate change. No sooner was one argument proved invalid (or in some cases, actually dishonest) than the contrarians came up with another.
In short, by 2001 policy-makers had gotten the best answer they were likely to hear for a long time. Meanwhile the new administration in the United States repudiated the international negotiations concluded so far, starting a new phase in the world's attempts to confront the issue. Ever since, the largest source of uncertainty about the future climate has not been in climate science, but in human social and economic choices — how much greenhouse gases would we decide to emit?
For basic information and current developments see the links page.
LINKS to the "After 1988" sections:
1. The panel’s final report, IPCC (2001), gives a good summary of the state of research at this point, including ten times more references than I have given to publications of the 1990s. There was also a scientific milestone in spring 2001: a convincing match between computer models and an observed rise of the oceans' heat content (more significant than atmospheric heat), helping to nail down the panel’s conclusion: Levitus, Antonov et al. (2001); Barnett, Pierce et al. (2001). BACK